fixed null db result bug

Author: aminroosta

example.cpp

@@ -1,90 +1,10 @@
 #include<iostream>
+#include<string>
+#include<tuple>
 #include "sqlite_modern_cpp.h"
 using namespace  sqlite;
 using namespace std;
 
-/*
-template <typename T>
-struct function_traits
-: public function_traits<decltype(&T::operator())>
-{};
-
-template <typename ClassType, typename ReturnType, typename... Args>
-struct function_traits<ReturnType(ClassType::*)(Args...) const>
-// we specialize for pointers to member function
-{
-enum { arity = sizeof...(Args) };
-// arity is the number of arguments.
-
-typedef ReturnType result_type;
-
-template <size_t i>
-struct arg
-{
-typedef typename std::tuple_element<i, std::tuple<Args...>>::type type;
-// the i-th argument is equivalent to the i-th tuple element of a tuple
-// composed of those arguments.
-};
-};
-
-class database_bind {};
-
-template<int N>
-class A {
-template<typename F>
-static void run(F l);
-};
-
-template<>
-struct A<1> {
-template<typename F>
-static void run(F l) {
-typedef function_traits<decltype(l)> traits;
-typedef typename traits::arg<0>::type type_1;
-
-type_1 col_1;
-get_from_db(0,col_1);
-
-l(col_1);
-}
-};
-template<>
-struct A<2> {
-template<typename F>
-static void run(F l) {
-typedef function_traits<decltype(l)> traits;
-typedef typename traits::arg<0>::type type_1;
-typedef typename traits::arg<1>::type type_2;
-
-type_1 col_1;
-type_2 col_2;
-get_from_db(0,col_1);
-get_from_db(1,col_2);
-
-l(col_1, col_2);
-}
-};
-
-
-void get_from_db(int col_inx, string& str){
-// code to get a column from with col_inx from the database
-// for simplicity
-str = "str_col";
-}
-void get_from_db(int col_inx, int& i){
-// just for simplicity
-i = 12;
-}
-
-
-template<typename F>
-void operator>>(database_bind dbb, F l)
-{
-typedef function_traits<decltype(l)> traits;
-A<traits::arity>::run(l);
-}
-
-*/
 
 int main(){
 	try {
@@ -101,7 +21,7 @@ int main(){
 
 		// inserts a new user and binds the values to ?
 		// note that only types allowed for bindings are :
-		//		int ,long, long long, float, double 
+		//		int ,long, long long, float, double
 		//		string , wstring
 		db << "insert into user (age,name,weight) values (?,?,?);"
 			<< 20
@@ -113,14 +33,14 @@ int main(){
 			<< L"jack"
 			<< 68.5;
 
-		// slects from table user on a condition ( age > 18 ) and executes 
+		// slects from table user on a condition ( age > 18 ) and executes
 		// the lambda for every row returned .
 
 		db << "select age,name,weight from user where age > ? ;"
 			<< 18
 			>> [&](int age, string name, double weight) {
-				cout << age << ' ' << name << ' ' << weight << endl;
-			};
+			cout << age << ' ' << name << ' ' << weight << endl;
+		};
 
 		// selects the count(*) of table user
 		// note that you can extract a single culumn single row answer only to : int,long,long,float,double,string,wstring
@@ -136,5 +56,4 @@ int main(){
 	catch (exception& e){
 		cout << e.what() << endl;
 	}
-
 }

sqlite_modern_cpp.h

@@ -129,12 +129,12 @@ namespace sqlite {
 #pragma region get_col_from_db			
 			void get_col_from_db(int inx, int& i){
 				if (sqlite3_column_type(_stmt, inx) == SQLITE_NULL) i = 0;
-				i = sqlite3_column_int(_stmt, inx);
+				else i = sqlite3_column_int(_stmt, inx);
 			}
 			void get_col_from_db(int inx, sqlite3_int64& i){
 				if (sqlite3_column_type(_stmt, inx) == SQLITE_NULL)
 					i = 0;
-				i = sqlite3_column_int64(_stmt, inx);
+				else i = sqlite3_column_int64(_stmt, inx);
 			}
 			void get_col_from_db(int inx, string& s){
 				if (sqlite3_column_type(_stmt, inx) == SQLITE_NULL) s = string();